The spelling here is appropriate for 1509-10. In the source documents I used, there was an odd quirk of combining 'the' with the following word if the following word began with a vowel. Thus 'thencresce' means "the increase" and 'thadvis' means "the advice."
Brennan Augustus and Caoilfhionn Augusta, callyng unto theire tendre remembraunce howe that in tymes passed unto nowe of late, the goode ladye Philadelphia Browne hath noblye, grately and honourably served the reaulme as Vicar, stiward, exchequer, and chastelayne to thencresce, availe and commen wele of all, as experience evydently hath proved; and, as it is well knowen that the seid Philadelphia is in all thyngs celebrable, cortious and stedfast; in consideration wherof, and by thadvis and assent of the lordes spirituelx and temporelx, and the commens, in this present court assembled, and by auctorite of the same, wolle of theyr gracious and bounteuous disposition, that it be ordeyned, establisshed and enacted, that the said Philadelphia be and herbye is elevated, avaunced and extollede to the Order of the Pelycan. Moreover, the seid Philadelphia shall bear hens-forthward armes by lettres patentes: Gyronny Or and gules, a broune mare raumpaunt proper. So ordeyning, establisshyng and enacting, the Emperor and Empress, of their bounteuous and benigne grace, by the advis and assent of the lordes spirituelles and temporelles, and the commens, in this present court assembled, and by auctorite of the same, wolle that it be also ordeyned, establisshed and enacted that all maner of privileges, libertees, fraunchises and free usages graunted unto the seid Philadelphia by these our pressent lettres stond in full strengh, force and effect, as they didde or shuld have doon for all other persones of the aforeseid Ordre since the foundement of the Society. And moreover, for the more suerte and certeynte of the same, the Emperor and Empress, by thadvis, assent and auctorite aforesaid, wolle that these lettres patentes under their ensygns manuelles be made to the seid Philadelphia, after the fourme and effect ensuyng; and that the same lettres patentes be by the seid auctorite good and available, after the tenour and fourme of the same. Doone upon 13 Septembre in the fortie-ninthe year of the Society in Iron Bog.